Wipers of a vehicle are means for securing a field of view of a driver and thus helping safe driving by removing raindrops falling on glasses of the vehicle, which are installed at the front and rear of the driver's seat, when the vehicle is running in the rain.
Such a wiper is configured to operate in response to switch manipulation of a driver when the vehicle is running in the rain.
In recent years, a technology has been developed to automatically operate the wiper for the sake of driving convenience of the driver without any necessity for the driver to manipulate the wiper separately during driving in the rain.
This technology can be achieved through a rain sensor that detects raindrops falling on the glass of the vehicle.
In this case, the rain sensor detects raindrops when the raindrops fall on the glass of the vehicle and then actuates the wiper, while it stops operation of the wiper when the raindrops are not detected.
Since such a rain sensor is configured to operate the wiper when raindrops are detected from the glass of the vehicle, the following problems may occur.
First, there is a problem that the wiper is operated even when raindrops fall at such a degree that there is no need to operate the wiper.
In particular, as technology has been developed in recent years, it is possible to automatically remove raindrops by spraying a specific liquid on the glass of the vehicle, which may cause raindrops falling on the glass of the vehicle to be automatically removed due to airflow generated during running of the vehicle. In this case, operating the wiper even when raindrops fall at such a degree that there is no need to operate the wiper will consume unnecessary power.
Second, since the rain sensor in turns uses electric power of the vehicle, there is a problem that accumulation of unnecessary operation of the wiper may affect discharge of the vehicle.
On the other hand, as a technology related to a rain sensor, a prism mediated type rain sensor is disclosed in Korean Laid-Open Patent Publication No. 10-2010-0010752.
The above document discloses a rain sensor to detect amount of rain more accurately by eliminating parameters unnecessary for infrared ray detection, wherein the rain sensor is configured to use a prism to reflect and refract infrared ray beam which is generated from an infrared ray LED and then emitted to a windshield glass of a vehicle and allow the infrared ray beam to be received from the windshield glass of the vehicle through a infrared ray filter and the prism again so that a structure for collecting light is simplified.
However, since the above document only discloses the structure of the rain sensor and does not disclose any configuration associated with the wiper of the vehicle, it cannot solve the problems as mentioned above.
Further, Korean Laid-Open Patent Publication No. 10-2012-0012269 discloses a device for detecting raindrops.
This document discloses a device for detecting raindrops that is capable of controlling operation of a wiper of a vehicle by detecting an amount of the raindrops, wherein the device comprises a light guide unit which is in close contact with a surface of a glass of the vehicle and allows incident guide light to be totally reflected from the surface of the glass, a light emitting unit provided at an incident side of the light guide unit to emit light source, and a light receiving unit provided at an output side of the light guide unit to filter a predetermined narrow band light from the light received.
The document also describes that a time period of operation of the wiper can be adjusted according to the amount of rainfall using information of raindrops detection from the device for detecting raindrops.
However, this document also describes only the device for detecting raindrops for operation of the wiper and cannot solve the problem that unnecessary operation of the wiper must be minimized.
Therefore, there is a need to develop a technology capable of detecting raindrops falling on a glass of a vehicle through a rain sensor and minimizing unnecessary operation of a wiper depending on an amount of raindrops detected.
In addition, there is a need to develop a technology capable of allowing the emitted light to be easily and totally reflected from a glass of a vehicle and assisting to receive the light totally reflected from the glass of the vehicle.
Furthermore, there is a need to develop a technology that can broaden a detection area for detecting raindrops falling on a glass of a vehicle.